The use of optical transmission media, such as optical fibres and integrated optics, as a high bandwidth channel, is insufficient by itself to implement high-capacity optical processing networks. The ultimate capacity of the channel will be limited by the processing speed of the associated electronics circuitry. Current stage-of-the-art electronic processing speeds are limited in the region of 1 GHz. However, optical processing methods potentially offer much higher processing throughput so that speeds may be pushed up to about 100 GHz.
Several fibre-optic networks utilising high bandwidth optical processing have been proposed recently. One such arrangement is based on an optical signal processor disclosed in international patent application Publication No. WO90/04823 in the name of the University of Strathclyde. In this arrangement, the optical signal processor and the method of processing provided a binary digit transformation so that after processing the digits, non-binary bits may be created. This required special non-standard circuitry to be manufactured to process the non-binary data. The special fabrication requirements for this circuit may limit the potential widespread use of the optical signal processor disclosed in the above publication.